Regenerative furnace and production of unsaturated hydrocarbons therein



J. W. BEGLEY REGENERTIVE FURNACE AND- PRODUCTION OF UNSATURATED HYDROCARBONS THEREIN March 12, 1957 4 Sheets-Sheet l Fled Nav. 29, 1954 Dumm nm f//f//O m.

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INVENTOR. J.W. BEGLEY A TTORNEYS March 12, 1957 .1. w. BEGLEY 2,735,212

REGENERATIVE FURNACE AND PRODUCTION OF' UNSATURATED HYDROCARBONS THEREIN Filed NOV. 29, 1954 4 Sheets-Sheet 2 I3 l2 ll To TIMER-r F/G. 5

INVENTOR. J.w. EEG LE Y ll l2 I3 27 24 March 12, 1957 1. .Br-:GLEY 2,785,212

REGENERATIVE FURNACE AND PRODUCTION 0F UNSATURATED HYDROCARBONS THEREIN -Filed Nov. 29. 1954 4 Sheets-Sheet 3 INVENTOR. J.W. BEGL EY v @Px 14n .l 4ms.; o w

A T TORNE V5 March 12, 1957 J. w. BEGLEnr` 2,785,212

REGENERATIVE FURNACE AND PRODUCTION OF UNSATURATED HYDROCARBONS THEREIN Filed nov. 29, 1954 4 sheets-sheet 4 INVENTOR. J.W. BEGLEY m. N. N

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YA 7' TORNE V5 United States Patent REGENERATIVE FURNACE AND PRODUCTION OF UNSATURATED HYDROCARBONS THEREIN John W. Begley, Ann Arbor, Mich., assigner to Phillips Petroleum Company, a corporation of Delaware Application November 29, 1954, Serial No. 471,816

18 Claims. (Cl. 260-679) This invention relates to the conversion of hydrocarbons. ln one of its more specific aspects, it relates to a novel regenerative furnace for use in the thermal cracking of hydrocarbons. In another of its more specic aspects, it relates to means for distributing fuel uniformly across 'the combustion section of a regenerative furnace.

During the early years of the petroleum industry, the possibility of producing unsaturated hydrocarbons by the cracking of low boiling hydrocarbons received comparatively little attention. Because of apparatus limitations imposed by the high reaction temperatures involved and the lack of understanding of the best manner of operation, early developments excluded the cracking of low boiling hydrocarbons. Still another deterrent in the development of successful processes was the availability of vast supplies of heavy naphthas which could be cracked by more easily manageable processes to form easily puriable products in high yield. Recent advancements made in organic chemistry have resulted in such an increased de mand for potro-chemical starting materials, such as acetylene and ethylene, that it is no longer possible to rely on the old sources of supply for these materials. The demand for ethylene has reached such proportions that it cannot be supplied from refinery streams without upsetting the balance in the production of motor and aviation fuels. Furthermore, commercial production of acetylene by reacting calcium carbide with water is too expensive and is limited to amounts far too low to satisfy the demand for acetylene as a chemical synthesis starting material. Accordingly, the development of successful processes for producing unsaturated hydrocarbons by the cracking of low boiling hydrocarbons has in recent years taken on added importance.

Various methods for the pyrolysis of gaseous hydrocarbons have been proposed which involve the use of a variety of heat sources, including externally heated tubes, electrically heated resistance elements, and spark or electrical discharges. The lack of cheap electric power has alsodrawn attention to other possible methods of heating, such as by the combustion of preheated natural gas with preheated compressed air. In such latter processes when utilizing regenerative furnaces, a stream of air and fuel gas is burned in, or hot combustion products passed through, a refractory checkerwork so as to heat it to a high temperature. After the hotv gases have heated the checkerwork to the desired temperature, the ilow of combustion gases is terminated, and thereafter the reactant materials to be treated are passed through the heated checkerwork in order to bring the materials to reaction temperature.

In a particularly useful regenerative furnace of this type, utilized for the thermal cracking of hydrocarbons, such as methane, ethane, propane or butane, to produce unsaturated hydrocarbons, such as ethylene or acetylene, an elongated checkerwork of refractory material is provided at either end of a central combustion chamber. Air is passed in one direction through one of the checkerwork ICC structures While a fuel gas is introduced into the central combustion chamber. The fuel gas and air burn in the combustion chamber, and thereafter the resulting combustion gases flow through one of refractory checkerworks. When this checkerwork has reached the desired temperature, the ow of air and fuel is terminated, and the materials to be cracked or otherwise converted are passed in the opposite direction through the heated refractory where the desired cracking or other reaction occurs.

After a timed reaction period, the ow of reactant materials is stopped, and air is passed through the furnace in a direction opposite to that of its first introduction. At the same time, fuel gas is introduced into the central combustion chamber to mix with the air and form a combustible mixture which is burned therein to form hot combustion gases to heat the refractory checkerwork downstream of the combustion chamber. When the checkerwork attains the desired temperature, the materials to be converted are passed through the heated refractory.

When using a regenerative furnace of the type described, having a central combustion chamber disposed between a pair of similar refractory checkerworks, for cracking light hydrocarbons, diiculty has been encountered in obtaining a uniform distribution of heat in the refractory masses. This unsatisfactory condition arises from the fact that on the regeneration cycle the combustion gases resulting from burning fuel gas and air within the combustion chamber have a tendency to channel through a portion only of the refractory masses, thereby causing some parts of the refractories to be heated to higher temperatures than other parts. Furthermore, the combustible mixture formed by the introduction of air and fuel into the central combustion chamber may be of non-uniform composition which will also result in non-uniform tem.- perature across the cross section of the furnace. Such uneven heating may result in damage to the refractories and additionally may have a deleterious eect upon the cracking reaction. With regard to the effect of non-uniform heating of the refractories upon the cracking reaction, during the process cycle, portions of the hydrocarbon feed are heated to higher temperatures than others, resulting in overcracking and undercracking of the feed. The net result of such a reaction is a low product yield accompanied by the formation of carbonaceous materials, which over a period of time renders the furnace inoperative. In accordance with this invention, means are provided for uniformly mixing the fuel and air or the hotter and colder combustion gases before they contact the main refractory masses in the cracking sections of the furnace. The heat is thereby evenly and uniformly distributed throughout the refractory masses, resulting in an ecient cracking reaction in which secondary reactions are reduced to a minimum.

The following are objects of the invention.

It is an object of the invention to provide an improved regenerative furnace for use in the thermal conversion of hydrocarbons.

Another object of the invention is to provide an improved method for the thermal conversion of hydrocarbons whereby overcracking and undercracking of the reactant materials are substantially eliminated.

Still -another object of the invention is to provide means for distributing fuel uniformly across the combustion section of a regenerative furnace.

Yet another object of the invention is to provide means for uniform mixing of fuel and air and of combustion gases prior to their contacting the main refractory masses of a regenerative furnace.

A further object of the invention is to provide means for obtaining uniform and even heating of the refractories of' a regenerative furnace by preventing' channeling of the gases throughY any one portion of the furnace.

hydrocarbons.

Y constricted passageways.

Vtcationwof theinvention, there are disposed within'the arsenic A still further object of the invention is to provide a regenerative furnace which includes means for distributing the gases evenly and uniformly throughout the furnace.

A Still further objects and advantages of `therinvention will become Vapparent to one skilled in the art upon .consideration of the following disclosure.

Broadly speaking, the present invention resides in a novel regenerative furnace which includes means for obtaining uniform heating of the refractory masses and the u se of such .a furnace in processes for the conversion of The regenerative furnace of my invention comprises a pair of refractory checkerworks separated by a combustion chamber having constricted passageways formed therein Vandhaving fuel inlets Yconnected thereto for injecting fuel into lair flowing through the In accordance with one modicombustion chamber two short refractory masses having longitudinal, parallel passageways into which fuel is in- Y jected `through conduits connecting the passageways to tubes which are in turn connected to a source of fuel gas. The aforesaid tubes extend through the short refractory masses between the longitudinal passageways either transversely from side to side or vertically from top to bottom. In another modification of the invention, two sets of tubes are utilized with each of the `short refractory masses, one set extending transversely from side to side and the other vertically from top to bottom. In still another modification` of the invention, a refractory column or core, elliptical in shape, is positioned within the combustion chamber so as to form a pair of constricted pasageways with two -of the chamber walls. A plurality of fuel inletsY connected to the Y combustion chamber provide means for introducing fuel into the constricted passageways,

A more complete understanding of the invention may -be yobtained by reference to the following description and the drawing, in which: t

Figure 1 is an elevation, partially in section, of Ya regenerative furnace in accordance with one modification 22 and 23 structed but shorter in length than main refractory masses 14 and 16, are positioned 'within combustion space 17. Refractory masses 22 and 23 are'spaced apart from one another and from the inner ends of refractory masses 14 and 16. Longitudinal passageways 24, substantially parallel to the longitudinal axis ofthe furnace, yare provided in refractory masses, 22 and V23. Longitudinal passage ways 24, as illustrated, each take the form of a venturi comprising a convergingnsection, a throat section and a diverging section. While it is `preferred to useventurilike constricted passageways in the short refractory masses in order to obtain a more efficient mixing of the fuel and oxidant, it is within the scope of the invention to utilize passageways substantially cylindrical in form.'V

Tubes 26 attend through each 'of the refractory masses between passageways 24V and substantially perpendicular to the axes of these passageways. While tubes 26 are shown as extending transversely `across re- Figure 4 is an elevation, in section, o f fa regenerative Y rial, such as two layers 12 and 13 of rebrick. The

inner layer 13-of insulating material is formed -of a more refractory material than router layer'12. Disposed within insulated shell 11 are refractory masses 14 `and 16 separated by a-combustion -space or chamber 17. Refractory masses Y14 and 16 are formed of refractory tiles similar to tiles 18 and Y19, las shown in Figure 3, which are arranged Ywithin the furnace with their longitudinal axes parallel to 'the longitudinal axis of shellY 1,1. The upper and lower faces of the tiles are provided with semicircular grooves 20 so that when thetiles `are pla-ced on top yof one another within shell V11, there is formed a series of openings 21. As shown in Figurel 1, openings 21 extend longitudinally through the refractory masses so as to provide passageways therethrough which communicate with kcombustion chamber 17. *Y

fractory masses 22 `and 2.3, it is to be understood that, alternatively, the tubes may pass through the Irefractory masses vertically from top to bottom without departing Y from the scope of Ythe invention. .Conduits V2V7cor'1nect passageways 24 with tubes 26, which are in turn connected to `a hea-der member' 28, as shown in Figure 2.

A fuel inlet line 29, affixed `to header member 28 -and containing a valve 31, provides ymeans for passing a fuel gas int-o tubes 26 and thence into passageways 24 through conduits 27. As illustrated in Figure l, eachof the refractory masses 22, 23 is provided with a header lmember 28 connected to a fuel inlet line 29. Refractory masses 22 and 23 and their associated passageways 24, tubes 26, conduits 27 and header members 28 each constitute fuel distribution means. Y

Plenum chambers 32 Vand 33, connected to the `ends of the regenerative furnace of Figure l, provide means for introducing reactant materials int-o the furnace. YEach of the plenum chambers may -be provided with a perforated distributor plate 34 to ensure even `distribution of the reactant materials through the refractory masses.

Conduit 36, through which hydrocarbon feed material is introduced, is connected by a three-way valve 37 toY a conduit 3S. Conduit 38 in yturn is connected throughY a three-way valve 39 to a conduit 41 which communicates with plenum chamber 32 or, alternatively, to a conduit 42 which communicateswith plenum chamber 33.y Valve 37 is also adapted to attach oxidant conduit 43 =to conduit 38 and, thence, to conduits 41 and 42, as

determined by the setting of valve 39. Conduits 41 and 42 are alsoselectively connected by a three-,way valve 44 to an effluent conduit 46 which leads to a product recovery system 47, or other disposal, as desired. Timer 4S is operatively connected to each of the valves 31 contained in fuel inlet lines 29 associated with each of the fuelY distribution means and to three-way valves 37, 39 and 44 to provide Valternate regeneration and process cycles. A timer suitable for controlling the cycles of operation is manufa-ctured by Taylor Instrument Companies, Rochester, New York.

Referring to Figures 4 and 5 Vof the drawing, there is shown another modication of the regenerative furnace of this invention. been used to designateY elements corresponding with those described in conjunction with Figure l. Refractory masses 51 and 52 disposed within combustion space i7 are provided with longitudinal parallel passagcways 54. While passageways 54- y.are illustrated as being substantially cylindrical in shape, they maybe in the form of a venturi as shown in Figure l. Tubes 56 extend transversely through refractory masses S1 and 52 betweenV passageways 54 while tubes 57 extend vertically from top to bottom through the refractory masses between passageways 54. It is noted .that transverse tubes 56 and vertical tubes 57 ,are oifset longitudinally from one another so that the two sets of tubes do not intersect Vwithin the reldentical reference numerals have fractory masses. Conduits 5S communicate transverse tubes56 with longitudinal passageways 54 while conduits 59 connect vertical tubes 57 with the same passageways, as shown in Figure 5. Transverse tubes 56 terminate in header member 61 while vertical tubes 57 are connected to header member 62. Fuel inlet lines 63 and 64, each provided with suitable flow control means and attached to header members 6E. and 62, respectively, provide means for introducing a fuel gas into the header members and thence into passageways 54 through transverse tubes 56 and vertical tubes 5'7 and conduits Sti and 59 connecting the tubes to the longitudinal passageways. As illustrated in Figure 4, each of the refractory masses 5l, 52 is provided with a pair of header members 6l, 62 connected to tubes 56 and 57, respectively. While a pair of header members are shown as being connected to the transverse and vertical tubes associated with each of the refractory masses 5l and 52, it is within the scope of the invention to utilize a single plenum chamber which encompasses the ends of tubes 56 and 57 of each fuel distribution means in order to provide for the introduction of a fuel gas. It is to be understood that conduits 41 and 42 connected to plenum chambers 32 and 33 can be further connected to a supply of oxidant and feed material through a valve system, as shown in Figures l and 2, and that a timer can be used in conjunction therewith to control the cycles of operation.

Referring to Figures 6 and 7 of the drawing, still another modication of the regenerative furnace of this invention is illustrated. Identical reference numerals have been used to designate elements corresponding to those described in conjunction with Figure l. A refractory column or core 66 having a substantially elliptical horizontal cross-section is disposed within combustion space 17 so as to form constricted passageways 67 and 68 with the side walls of the combustion chamber. It is noted that the long axis of the elliptical cross-section of the column is substantially parallel to the axis of the furnace and that the constricted passageways are each shaped as half-venturi sections. While column 66 is shown as extending substantially vertically between the top and bottom walls of the combustion chamber, it is to be understood that the column may be disposed between the side walls of the chamber so as to form constricted passaveways with the top and bottom walls of that chamber. A plurality of fuel inlets 69, connected to each of the side walls of the furnace, communicate with constricted passageways 67 and 68, preferably at the narrowest portion of these passageways. As illustrated in Figure 7, a header member 71 is connected to each of the fuel inlets 69 and to fuel inlet line 72 which is provided with a flow control means 73. lt is to be `understood that conduits 41 and 42 connected to plenum chambers 32 and 33 can be further connected to la supply of oxidant and feed material through a valve system, as shown in Figures l and 2, and that a timer can be used in conjunction therewith to control the cycles of operation.V

The regenerative furnaces of this invention are especially adapted for carrying out processes for the production Vof unsaturated hydrocarbons, such as acetylene, ethylene, Vand mixtures of acetylene and ethylene. The reaction ytemperatures for such'processes will vary in the approximate range of l250 F. to 2700 F. More specifically, in the acetylene process, the reaction temperature is preferably maintained between about 2200" F. and 2700 F., in the process for the production of acetylene and ethylene, between about l700 F. and 2200 F., and in the ethylene process, between about l250 F. and l700 F. The reaction times `for the several processes are in the following approximate ranges: for acetylene, between 0.000l,and 0.2 second; for a mixture of acetylene and ethylene, between 0.01 and 0.2 second; and for ethylene, between 0.01 and 2 seconds. From this consider-ationof reaction temperatures and reaction times,

6 it is apparent that the 'reaction tim'es vary inversely the reaction temperatures, i. e., the higher the reaction temperature, the shorter the reaction time.

A wide variety of hydrocarbon feed stocks can be used in the practice of the processes of this invention. Those which can be suitably used include methane, ethane, propane, butane and mixtures of these hydrocarbons and/or their corresponding olefins. It is to be understood, however, that any vaporizable or gaseous hydrocarbons can be advantageously employed as the feed. it is also within the contemplation of the invention to use a diluent such as steam with the hydrocarbon feed in order to reduce the deposition of carbonaceous materials Within the furnace.

Oxidants which can be used in the process of this invention include oxygen, air, and oxygen-enriched air. Any suitable fuel, preferably a clean burning fuel, can be utilized in the practice of this invention. Gaseous or liquid hydrocarbons are preferably used as fuels, and process olf-gases from the process of this invention or other processes can be advantageously employed; When using a liquid hydrocarbon, the fuel is introduced into the furnace in vaporizedform.

In the operation of the regenerative furnace of Figure l, during the regeneration cycle three-Way valves 37 Aand 39 are in such a position that an oxidant, such as air, is forced by a blower (not shown) through conduits 43, 38 and 4l into plenum chamber 32, from which it passes into passageways 21 of refractory mass 14. Plenum chamber 32 and perforated distributor plate 34 disposed therein provide for even distribution of air across the face of refractory mass 14 and assure even llow of air therethrough. It is assumed that the furnace has been previously brought to operating temperature during astai'tup cycle in which fuel and air passed into the furnace are ignited by a suitable ignition means, e. g., a burning torch introduced into the combustion chamber. The resulting combustion products are then passed through the furnace until it is preheated to the desired temperature.

The air, in passing through refractory mass 14, is heated to a temperature at least as high as the' ignition -temperature of a fuel gas to be introduced into passageways 24 of refractory mass 22. The heated air issuing from refractory mass 14 is redistributed in refractory mass 22 and mixed with a fuel gas inpassageways 24 of this refractory mass. The fuel gas, which may be preheated, is introduced into passageways 24 of refractory mass- 22 through fuel inlet line 29, header' member vr28, tubes 26 and conduits 27. The air and fuel are mixed Within passageways'24, forming a combustible mixtureV which burns therein and in the space between refractory masses 22 and 23. By introducing fuel into a pluralityvof air streams in this manner a thorough mixing of air and fuel is obtained so as to provide a combustible mixture of uniform composition. The resulting combustion products are redistributed by means of refractory mass 23, passing through passageways 24 of this mass prior to entering refractory mass 16. As a result of the redis.- tribution of the combustion gases by refractory mass 23, channeling of the gases through one portion only of refractory mass 16 is prevented, andthe gases flow evenly and uniformly therethrough. And because of'this uniform and even ow of combustion gasesithrough refractory mass 16, substantially no differential in temperature exists across any cross section of the refractory mass. After passing through refractory mass 16 and heating same to the desired temperature, the combustion products ow into plenum chamber 33 and, thence, through conduits 42 and 46 into product recovery system 47 where they may be used for heating or other purposes.

At the conclusion of a predetermined time interval,`

as determined by the setting of timer 48, valve 37 is. actuated by the timer to transfer conduit 38 from its con` nection with conduit 43 to a connection ,with conduit.`

Ihe timer .also operates to ,close Nahe kitl in the;

autres? l f v7 Y Y@.1 inlet .lineZS .of header ine. ber 2,3 ,asse 'ated with intresten' mass 22 and to rever-.Se :the settingsnf valves ,3,9 and f1.4'

so that conduit 3.8 is Connected t Conduit $2 and Conduit 41 vis.,Connected to .conduit 46- An interval of .one mnute ;,is a suitable Vreaction period and regeneration period for the cracking of propane -toform acetylene. Thetirne interval will, in general, depend upon the specific process` sired .cracking ktemperature and undergoes reaction. The

cracked hydrocarbon vfeed thereafter passes into Ycornbustionv space i and through passageways 24 of refractory masses 23 and 22. ln passing through refractory masses 22 and 23, the reaction products are'redistributed priorto entering main refractory mass 1,4 .which has preyiously ibeen `cooled on :the regeneration cycle .bypassage `of fair -therethrough.V vIn flowing through refractory Y mass i4, kthe reaction products are rapidly quenched to 'aV-temperature :at which they are stable, e. g., to a temperature in the `rangeof about 400 F. to ltlGO" F. v The reaction products then vflow into plenum chamberrSZ and are subsequently passed through conduits 4i and 46 to product recovery systcmi47 for separation of the productV gas `from the reactionrproducts.

"At the end of the V*predetermined time interval, timer 48 operates to change the setting of valve 37 so that air ishow introduced Vinto the regenerative furnace through conduit .4Z-to start the regeneration cycle. functions also to open'fuel valve 31 contained in fuel -inletfline 29 of headermember Y28 associated with refractory mass 23, thereby allowing fuel to ow into :passageways 24of -refractory Vmass 23,.' The regeneration cycle -s lcarried .out in the same mannerV as previouslyV described .except that air is now introduced into the regenerative furnace 4:from an end opposite to its frst introduction', andfuel -is introduced into the longitudinal '46, Ther-regeneration and-process cycles are thereafter ,repeated :at Vthe predetermined time intervals to produce the Vdesired product.

The operation of the apparatus of .Figure 4 is vessen- -tiallythesame as that of Figure l except for the manf ner 'in which fuel gas is -introduced into the furnace.

Accordingly, during the regeneration cycle fuel gas is `introduced into passageways A54 through transverse tubes V`r56 and conduits 158 and vtlirough -vertical tubes 57 and conduits y59. 'Fuelgas is, therefore, being injected into 'longitudinal passageways 54 `of ,refractory masses 51 or The timer "As previously noted in' C eninstio with the' descrintign either Side 0f the .furnace attaining .its greatest ylity in the narrar/est ian .0 the conducted -nassesew of Figure 6,V )the fuel is preferably,introducedinto (the constricted passageway/s at theirnarrowest portion. he

fuel and air impinge in the narrowest portions'ofthe constricted passageways creating therein a condition of extreme turbulence with the result that the fuel and air Vare rapidly and uniformly mixed. By operating in ythis manner, uniform `mixing of the gases is accomplished before they contact the main refractory masses of the furnace, and the mixing is done in a shorter distance than would be required if constricted passageways were.

not provided in the combustion space. 'n 'Y ltr/ill be apparent that by utilizing the regeneratiye furnace of this invention in the conversion ofY hydrocarhons, it is possible to obtain an improved' craclgirlgY Y reaction. By providing a regenerative furnace in which uniform mixing of fuel and air or of :hotter and colder combustionV gases is obtainable before the gases Contact the main refractory checkerworlrs, uniform andV even heating of the refractory chcelierv/ orks vis made possible with the result'that overcr'aching'anrl undercracking of the hydrocarbon `feed is substantially eliminated. By preventing overand undercraekingV of the hydrocarbon feed, the formation of carhonaceous materials, which may result in furnace shutdown, is obviated. Further-V more, by substantially eliminating the occurrence Vof `secondary reactions, a product yield is made possible which is higher than that obtainable with conventional furnaces.

As will be evident to those skilled inthe art, various f chamber in alignment withthe main refractory masses Y disposed therein, the improvement which comprises a rst 52, as applicable, at Vfour different points with the result -that an'increased.turbulenceis 'set upV within the passage- .'Iwaysof-therefractory masses. Because of this increased rturbulence, a morethoroughmixing ofthe `fuel and air Y is :made possible, and a more ,efficient combustion re- -action'taites place.

-irng1thelregenerationcycle-'fuel gasY isintroduced iinto con- :str'icted ypassageways '.67 and 63 Vvof combustion gspace 17 through :fuel Ainlets .69. fllhc Aair on .entering Ithe `combustionchamber hows around elliptical column vnear and a second refractory mass positioned Within said combustion chamber, said masses being lspaced apart from one another and from said main refractory masses; passageways extending through said rst'and second refractory massesy substantially parallel to theraxis of said fur` V2. ln a regenerative furnace'comprising at Vleast Jtwo main refractory masses Vdisposed in longitudinal .alignment and spaced apart so as to form acombustion charnber therebetween and having passageways therethrough parallel to the axis of said furnace and communicating with said combustion chamber, the Vimprovement which comprises a pair ofY perforate gas Ydistribution members formed of refractory material positioned within said combustion chamber, said members being spaced apart ufrom one another and from said main refractory masses` and means for laterally introducing fuel into the perforations of said gas distribution members.

3. In a regenerative furnace comprising at least two main refractory masses spaced apart so as to form a combustion chamber therebetween and vhaving passagewaysV therethrough communicating with said combustion chamber, the improvement which comprisesY a first Vand-a ySecmain refractory masses; second passageways extending through each said r'st'and second refractory masses :and positioned between said rst passageways; conduits 'extendingthrough.said rst and second refractory masses Yccgrrnnunicating V,said first passageways .with said second passagewaysgrneans for laterally introducing a fluid hito said second ,YpassageyntysV of v,said vvtirst refractory ass;

and means for laterally introducing'va. fluid into Vsaid second passageways of said second refractory mass.

4. In la regenerative furnace comprising at least two main refractory masses spaced apart so as to form a combustion chamber therebetween of substantially rectangular cross-section and having passageways therethrough cornmunicating with said combustion chamber, the improvement which comprises a refractory column positioned within and extending between two opposite Walls of said combustion chamber, said column having a substantially elliptical horizontal cross-section, the long axis of said cross-section being substantially parallel to the axis of said furnace; a pair of constricted passageways formed between said column and two of the walls of said combustion chamber; and means for introducing fuel into said constricted passageways.

5. A regenerative furnace which comprises, in combination, an elongated shell; a first refractory mass disposed in one end portion of said shell; a second refractory mass disposed in the other end portion of said shell, said refractory masses having passageways extending therethrough substantially parallel to the longitudinal axis of said shell; a combustion chamber disposed within said shell between said rst and second refractory masses; a third and a fourth refractory mass, each substantially shorter in length than said iirst and second refractory masses, disposed within said combustion chamber, said third and fourth refractory masses being spaced apart from one another and from said iirst and second refractory masses; rows of longitudinal openings formed in each said third and fourth refractory masses so as to provide longitudinal passageways therethrough which are substantially in horizontal and vertical alignment; transverse openings formed in and extending across each said third and fourth refractory masses between said rows of longitudinal openings so as to provide transverse passageways therethrough; conduits formed in each said third and fourth refractory mass communicating said transverse passageways with said longitudinal passageways; means for introducing a uid into said transverse passageways of said third refractory mass; means for introducing a uid into said transverse passageways of said fourth refractory mass; and means for passing air and material to be converted into and through said refractory masses.

6. The regenerative furnace of claim in which each said longitudinal passageway is in the form of a venturi comprising a diverging section and a converging section connected by a throat section and said conduits communicate with said passageways at said throat section.

7. A regenerative furnace which comprises, in combination, an elongated shell; ya first refractory mass disposed in one end portion of said shell; a second refractory mass disposed in the other end portion of said shell; said refractory masses having passageways extending therethrough substantially parallel to the longitudinal axis of said shell; a combustion chamber disposed within said shell between said rst and second refractory masses; a third and a fourth refractory mass, each substantially shorter in length than said iirst and second refractory masses, disposed within said combustion chamber, said third and fourth refractory masses being spaced apart from one yanother and from said first and second refractory masses; rows of longitudinal openings formed in each said third and fourth refractory masses so as to provide longitudinal passageways therethrough which are substantially in horizontal and vertical alignment; vertical openings formed in and extending from top to bottom each said third and fourth refractory masses between said rows of longitudinal openings so as to provide vertical passageways therethrough; conduits formed in each said third and fourth refractory masses communicating said vertical passageways with said longitudinal passageways; means for introducing a uid into said vertical passageways of said third refractory mass; means for introducing i Y 10 t a fluid 'into said vertical passageways of said fourth refractory mass; and means for passing air and material to be converted into and through said refractory masses.

8. The regenerative furnace of claim 7 in which each said longitudinal passageway is in the form of a venturi comprising a diverging section and a converging section connected by a throat section and said conduits communicate with said passageways at said throat section.

9. The regenerative furnace of claim 8 in which said conduits intersect said throat section at points diametrically opposite one another.

10. A regenerative furnace which comprises, in combination, an elongated shell; a lirst refractory mass disposed in one end portion of said shell; a second refractory mass disposed in the other end portion of said shell, said refractory masses having passageways extending therethrough substantially parallel to the longitudinal axis of said shell; a combustion chamber disposed within said shell between said rst and second refractory masses; a third and a fourth refractory mass, each substantially shorter in length than said iirst and second reactory masses, disposed within said combustion chamber, said third and fourth refractory masses being spaced apart fromy one another and from said first and second refractory masses; rows of longitudinal openings formed "in each said third and fourth refractory masses so as to provide longitudinal passageways therethrough which are substantially in horizontal and vertical alignment; transverse openings formed in and extending across each said third and fourth refractory masses between said rows of longitudinal openings so as to provide transverse passageways therethrough; vertical openings formed in and extending from top to bottom each said third and fourth refractory masses between said rows of longitudinal openings so as to provide vertical passageways therethrough, said vertical openings being offset longitudinally from said tranverse openings; conduits communicating said longitudinal passageways with said transverse passageways and said vertical passageways; means for introducing a iluid into said transverse and vertical passageways of said third refractory mass; means for introducing a uid into said transverse and vertical passageways of said fourth refractory mass; and means for passing air and material to be converted into and through said refractory masses.

l1. The regenerative furnace of claim l0 in which each said longitudinal passageway is in the form of a venturi comprising a diverging section and a converging section connected by a throat section and said conduits communicate with said passageways at said throat section.

l2. The regenerative furnace of claim l1 in which said conduits communicating said longitudinal passageways and said transverse passageways are diametrically opposite one another and said conduits communicating said longitudinal passageways and said vertical passageways are diametrically opposite one another.

13. A process for the conversion of hydrocarbons which comprises passing heated air into a combustion zone; owing Said air through a portion of said cornbustion zone as a plurality of air streams; introducing fuel laterally into said plurality of said streams so as to form a plurality of combustible mixtures of substantially uniform composition; burning said combustible mixtures within said combustion zone; redistributing the resulting combustion products within said combustion zone by flowing same as a plurality of gas streams through another portion of said zone; passing said combustion products from said combustion zone into a refractory checkerwork; flowing said combustion products evenly and uniformly through said refractory checkerwork so as to heat said checkerwork; terminating the supply of air and fuel to said combustion zone; passing material to be converted through said refractory checkerwork and smd combustion zone to effect the desired conversion; and withdrawing converted material from said combustion zone.

'Y ing substantially diametrically opposed.

. ll 15,1. process of claim13 in whch said fuelis i117- tally intofeach said'llair strans jat'twolsuhstamani;di.ftmtri1tybpposd piiinfs I ST-lzlep/r'ocess fof claim'13 'i'wliich ksaid fuel is introduced laterally into each Vsaid airstreams at four points,v the rst two of said points' being` substantially VVdiametrically vopposed and offset longitudinally frornthe secondrtwo of said points, said'secon'd two points also `be,-

"116. A process fo'rlhe come'rsion of hydrocarbons which comprises passing air through a rstfreir'acory Y,

Vchteclienwork invorder to heat saidaii; passing said heated air intoy a combustion zone; Yflowing said air Vthto'uglzt a portion of said combustion zone Vas a plurality of air s streams; Virnr-oduting fuel laterally into said plurality of air Y Vstreams so as to forrn a plurality of combustible mixtures ofV substantially uniform composition; 1 burning said combusrtille mixtures within said combustion zoneg'redist'ributing the resulting combustion products within said cornbustion zonerby flowing Sande as a plurality ,of Vgas streams v tltrolslgh.anothg-:r portion of said/Zone; passing said combustion products from saidcombustion zone into avseco'nd refractory'cheeizerwork; towing said combustion products evenlyV and uniformly through said second refractory lchecker/vork ,so as to heat saidv checkerwork; terminating Ytile supply of airand fuel to said Combustion zone; passing material to be converted into and through said second re- E v g Y s V lractory checkerwork 1n older to effect the deslred conyersion; passing the resulting reaction products into said #12 Y Y Hilfe. .saisi Eesti@ Pmduts s mail] amasfapluramy ,ofgas str ttok ghportlonsKoflsaidgon;Vpgssingsaid product vfi-m said 4combustion one into ysaid rstrefrsactory checkerwork; flowing said reactiontprrodcliteolierv/orl ,order .to cool said products lto a temper lattire at ,theyuarhe stable; .and Aremoving said cooled kreaction products from ,said rst refractory checkerwork.

Y 1-72lhe processl 7:7176 vin which said fuel Yis in; tx'o-fluce'; -laterally into each said .airrstreams at two sub-V Y stantia'lly diametriiallyi opposed points.V Y s Y flS'. The .proc'evssof Vclain 16 in V'which said fuel is introducedlaterallylinto eacl'said air streams atfour points, the yrsttwo ofsaidlpoirits beingsubstantially diarnetrieally opposed and'otst longitudinally from the .second two of said points, said second twompioin/ts also being substantially'zdiametricallyopposed@ Refeeteegs @tied in the file of Ythis'p'atent 

1. IN A REGENERATIVE FURNACE HAVING A COMBUSTION CHAMBER IN ALIGNMENT WITH THE MAIN REFRACTORY MASSES DISPOSED THEREIN, THE IMPROVEMENT WHICH COMPRISES A FIRST AND A SECOND REFRACTORY MASS POSITIONED WITHIN SAID COMBUSTION CHAMBER, SAID MASSES BEING SPACED APART FROM ONE ANOTHER AND FROM SAID MAIN REFRACTORY MASSES; PASSAGEWAYS EXTENDING THROUGH SAID FIRST AND SECOND REFRACTORY MASSES SUBSTANTIALLY PARALLEL TO THE AXIS OF SAID FURNACE; AND MEANS FOR LATERALLLY INTRODUCING FUEL INTO SAID PASSAGEWAYS.
 13. A PROCESS FOR THE CONVERSION OF HYDROCARBONS WHICH COMPRISES PASSING HEATED AIR INTO A COMBUSTION ZONE; FLOWING SAID AIR THROUGH A PORTION OF SAID COMBUSTION ZONE AS A PLURALITY OF AIR STREAMS; INTRODUCING FUEL LATERALLY INTO SAID PLURALITY MIXTURES SO AS TO FORM A PLURALITY OF COMBUSTIBLE MIXTUES OF SUBSTANTIALLY UNIFORM COMPOSITION; BURNING SAID COMBUSTIBLE MIXTURES WITHIN SAID COMBUSTION ZONE; REDISTRIBUTING THE RESULTING COMBUSTION PRODUCTS WITHIN SAID COMBUSTION ZONE BY FLOWING SAME AS A PLURALITY OF GAS STREAMS THROUGH ANOTHER PORTION OF SAID ZONE; PASSING SAID COMBUSTION PRODUCTS FROM SAID COMBUSTION ZONE; INTO A REFRACTORY CHECKERWORK; FLOWING SAID COMBUSTION ZONE INTO A REFRACTORY CHECKERWORK; THROUGH SAID REFRACTORY CHECKERWORK SO AS TO HEAT SAID CHECKERWORK; TERMINATING THE SUPPLY OF AIR AND FUEL TO SAID COMBUSTION ZONE; PASSING MATERIAL TO BE CONVERTED THROUGH SAID REFRACTORY CHECKERWORK AND SAID COMBUSTION ZONE TO EFFECT THEDESIRED CON VERSION; AND WITHDRAWING CONVERTED MATERIAL FROM SAID COMBUSTION ZONE. 